🍗 Section 4: Add Shared Actions (Feed / Play / Clean)

📝 Summary (What you will do)

In this section, you will add the first real gameplay actions to your Animal class:

feed() (hunger goes down, happiness goes up a little)
play() (happiness goes up, but hunger goes up too)
clean() (cleanliness goes up, happiness goes up a little)

Each method will:

Change the animal's internal stats (self._hunger, self._happiness, self._cleanliness)
Use clamp() so stats never go below 0 or above 100
Return a message string the UI can print

✅ Checklist (You must complete these)

Open pet_manager.py
Find class Animal
Find def is_struggling(self) -> bool:
Add the three methods (feed, play, clean) right after is_struggling()
Make sure your indentation is correct (these methods must be inside the class)

✅ No new constants/settings are added in this section, so you do not need to edit the top-of-file constants.

🎓 Core Concepts (New learning for this section)

1) Methods that modify object state

So far, we mostly stored data inside the object. Now we're adding behavior that changes that data.

Example:

feed() lowers hunger
play() increases happiness but also increases hunger
clean() increases cleanliness

This is the OOP idea of objects having both:

data (stats)
behavior (actions)

2) `clamp()` prevents broken stats

These actions can push stats past their limits.

Hunger should not go below 0
Happiness should not go above 100

That's why we do things like:

self._hunger = clamp(self._hunger - self.feed_power())

No matter what happens, clamp() keeps the value in a safe range.

3) Returning strings for the UI

Each action returns a string (a message) so the UI can do something like:

print(pet.feed())

This keeps the Animal class responsible for describing what happened, and the UI responsible for displaying it.

4) Calling helper methods (hooks)

You'll notice methods like:

self.feed_power()
self.play_power()
self.clean_power()

These are hook methods that make it easy for different animal species to behave differently later.

For now, just type the code exactly as shown. We'll build the hook methods soon.

💻 Code to Write (Type this by hand in `pet_manager.py`)

Directions:

Open pet_manager.py
Find class Animal
Find is_struggling()
Right after is_struggling(), type the following code by hand:

🧠 Code Review & Key Concepts (What important lines do)

The `before = (...)` tuple

before = (self._hunger, self._happiness)

This stores the "before" values so the message can show a before/after change like:

Hunger 45->25

Changing stats with `clamp()`

self._hunger = clamp(self._hunger - self.feed_power())

This line:

subtracts an amount from hunger
clamps the value so it stays between 0 and 100

Calling `self._gain_xp(ACTION_XP)`

self._gain_xp(ACTION_XP)

This rewards XP for taking an action.

If your code doesn't fully work yet after this section, that's okay:

We are calling a method (_gain_xp) that we will build in a later section.

Returning a message with an f-string

return f"{self._name} munches happily. Hunger {before[0]}->{self._hunger}, Happy {before[1]}->{self._happiness}"

This builds a string using an f-string:

{self._name} inserts the animal's name
{before[0]} uses the old value we saved
{self._hunger} uses the new value after the change

🧪 Test File: `s4_test.py`

✅ Create this file

Create a new file in the same folder as pet_manager.py called:

s4_test.py

💻 Code to write in `s4_test.py`

🧠 What this test is doing (and how it works)

Animal is abstract, so we create TestAnimal to implement special_action()
Section 4 calls feed_power(), play_power(), clean_power(), and _gain_xp(): this test provides those methods so the new actions can run now
We set _hunger, _happiness, and _cleanliness to known values so the test is predictable
After each action, we print the expected value and the actual value
The final check makes sure clamp() stops hunger from going negative

✅ Run the test:

python s4_test.py

If your output matches the "Expected ... got ..." lines, your Section 4 code is working correctly.